Field control devices having pre-defined error-states and related methods

ABSTRACT

Control apparatus having pre-defined error-states and related methods are described. An example non-transitory computer-readable medium disclosed herein comprises instructions that, when executed, cause a machine to analyze, via a controller coupled to a field device, a communication from a control system remotely located from the controller, the control system to operate the field control device during a non-error condition; detect an error condition while the field control device is communicatively coupled to and receives the communication from the control system; and override the communication between the control system and the controller to operate the field control device based on a pre-defined error-state instruction stored in the controller when the error condition is detected to cause the field control device to move to a first position for a first amount of time and subsequently move the field control device to a second position for a second amount of time, the first position being different than the second position.

RELATED APPLICATION

This patent arises from a continuation of U.S. patent application Ser.No. 13/280,060 (Now U.S. Pat. No. 8,812,914), filed on Oct. 24, 2011,entitled FIELD CONTROL DEVICES HAVING PRE-DEFINED ERROR STATES ANDRELATED METHODS, which is hereby incorporated herein by reference in itsentirety.

FIELD OF THE DISCLOSURE

This patent relates to field control apparatus and, more specifically,to field control devices having pre-defined error-states and relatedmethods.

BACKGROUND

Process control systems use a variety of field devices to control and/ormonitor process parameters. Field devices, such as valves, typicallyhave associated instruments, such as a valve position controller and/ora position transmitter, that control a position of the field deviceand/or transmit information about the field device to implement one ormore desired process(es) and/or operation(s) within a process plant. Anexample valve assembly includes a diaphragm-type pneumatic actuator,which is controlled by an electro-pneumatic valve position controller.The valve position controller receives, for example, a control signalfrom a control unit or system (e.g., a control room system) and convertsthe control signal(s) into one or more pneumatic pressures that areprovided to the pneumatic actuator to open, close or hold a position ofa corresponding field device or valve. However, in some instances, theprocess system may experience an error or fail condition that may affectthe accuracy and reliability of the valve. For example, communicationbetween the controller and the control system may be interrupted orstalled. In such instances, the controller cannot receive a signal fromthe control system, thereby causing the flow control device to remain inits last position or condition.

SUMMARY

An example method of operating a field control device described hereinincludes receiving, via a controller coupled to the field controldevice, a communication from a control system remotely located from thecontroller to operate the field control device during a non-errorcondition, detecting whether an error condition has occurred, andoperating the field control device based on a pre-determined error-stateinstruction stored in the controller when the error condition isdetected.

Another example method of operating a flow control system describedherein includes monitoring an operating parameter of a process controlsystem, detecting an error condition based on the operating parameter,and controlling a field control device via a local controlleroperatively coupled to the field control device based on at least onepre-determined error-state setting or instruction stored in thecontroller when the error condition is detected.

An example field control system described herein includes a fluidcontrol device to control a fluid flow of a process fluid and acontroller mounted to the field control device. The controller isoperatively coupled to the field control device and is configured toreceive a command from a system remotely located from the controller tocontrol a position of the field control device. The controller has alocal control system to command the field control device based on apre-defined error-state setting stored in the local control system whenan error condition is detected.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a process control system having an example controllerapparatus described herein.

FIG. 2 is a schematic illustration of the example controller apparatusof FIG. 1.

FIG. 3 is a flowchart representative of an example method that may beimplemented with the example controller apparatus of FIGS. 1 and 2.

FIG. 4 is a flowchart representative of an example process that may beused to operate the example controller apparatus of FIGS. 1 and 2.

FIG. 5 is a flowchart representative of an example process of FIG. 4 todetect an error condition.

FIG. 6 is a block diagram of an example processor system that may beused to implement the example methods and apparatus described herein.

FIG. 7 is a flowchart representative of an example method of installingthe controller apparatus described in FIG. 1.

DETAILED DESCRIPTION

The example apparatus and related methods described herein enable afield control device or field device (e.g., a valve, a pump, a vent, alouver, a final control element, etc.) or, more generally, a finalcontrol element to operate based on a pre-defined error-state settingwhen an operating condition and/or parameter deviates from a non-errorcondition or non-fail condition (e.g., a normal operating condition).Deviation from a non-error condition may affect the functionality of thefield device and/or may affect the ability to control the field device.As a result, if an error condition occurs, a field device may remain inits last current position, provided that a control fluid (e.g., air,hydraulic oil, etc.) to the field device is in a non-fail condition.

For example, one known field device (e.g., a valve) may be coupled to acontroller (e.g., a valve positioner, a transceiver, a transducer, etc.)having a communication interface to receive a process control signalfrom a control system remotely located from the controller. In someinstances, for example, when electric power to a control system isinterrupted, communication between the control system and thecommunication interface of the controller may be lost. Withoutcommunication to the controller, the controller cannot receive a signalor instruction to control the field device. Thus, known field devicestypically do not move to an error-safe condition when the controllerdetects an error-condition (e.g., communication between the controllerand control system is interrupted).

Unlike known field devices, the example apparatus and related methodsdescribed herein enable control of a final control element or a fieldcontrol device (e.g., a fluid control assembly) when an operatingcondition or parameter (e.g., a network connection status) deviates froma non-error condition. Example field devices, final control elementsand/or fluid control apparatus may include, for example, a fluid or flowcontrol valve, a pump, a vent, a louver, an actuator such as a pneumaticactuator, hydraulic actuator and/or any other field device(s) and/orfinal control element(s). Unlike known controller apparatus, the examplecontroller apparatus and related methods described herein employ a localcontrol process and/or logic circuitry to provide pre-definederror-state instructions or commands when an operating parameter and/orcondition of a process control system and/or a field device deviatesfrom a non-error condition.

For example, an example controller apparatus described herein may causea field device to move to a pre-defined error-state condition when anerror condition is detected. The pre-defined error-state condition(s)and/or instruction(s) or setting(s) may be user selected, user definedand/or programmable via, for example, an input interface of an examplecontroller apparatus described herein. In some examples, an examplecontroller apparatus described herein may prompt a user to select oractivate one or more pre-defined error-state condition(s) or setting(s)from, for example, a table or list. As a result, a controller apparatusdescribed herein can respond to an error condition even if a controlsystem and/or other control apparatus of a process control system cannotcommunicate with the example controller apparatus described herein.

A user-defined or pre-defined error-state condition may correspond todetection of a communication interruption between a remotely situatedcontrol system (e.g., a control room or system) and the controllerapparatus described herein. As a result, a local control system or logiccircuit of the example controller apparatus described herein may controlor operate a field device or flow control assembly based on apre-defined error-state setting or instruction stored or configured inthe example controller apparatus. For example, an error-state setting orinstruction described herein may include moving a field device to anopen position, a closed position, a throttling position, any positionbetween a fully open or a fully closed position when, for example, acommunication interruption is detected.

A user-defined error condition described herein may include detection ofa temperature surrounding an example controller apparatus describedherein that is greater than a temperature threshold value. In someexamples, an error condition described herein may occur when acalibration value of the controller apparatus and/or field devicedeviates from a pre-set calibrated range. In other examples, an errorcondition described herein may occur when a measured position value ofthe field device does not correspond to a command position valueprovided to the example controller apparatus by a control system of aprocess system.

In some examples, a pre-defined error-state setting or instruction mayinclude positioning a field device (e.g., a valve) to a position betweena first or fully open position (e.g., 100 percent stroke) and a secondor fully closed position (e.g., zero percent stroke). Additionally oralternatively, in some examples, a pre-defined error-state setting orinstruction may include positioning the field device in a first positionfor a first duration or amount of time after detection of an errorcondition and positioning the field device in a second position for asecond duration or amount of time after the expiration of the firstduration if the error condition persists after expiration of the firstduration. The first position may be different than the second position.

Additionally or alternatively, in some instances, the field deviceoperation may be dependent on an operation and/or position of anotherfield device in the process control system (e.g., an interlock process,a cascade process, etc.). In such instances, the example controllerapparatus described herein may delay, ignore and/or override a controlsignal (e.g., a coordinated signal) provided by the control system whenthe other field device is not properly positioned when the controllerapparatus receives the control signal. Additionally or alternatively,the controller apparatus may broadcast a warning or maintenance signalto the control system to alert a control room operator that the otherfield device is not properly positioned.

Additionally or alternatively, the example controller apparatusdescribed herein may be used to detect or provide diagnostic informationand an alert (e.g., a maintenance alert) when, for example, a valve doesnot move as expected, has stayed in a certain position for too long,maintenance has not been performed as expected, etc. In some examples,the controller apparatus described herein can initiate an automaticmaintenance routine (e.g., to cycle the field device) based on auser-defined schedule (e.g., periodically operate a valve to prevent aflow control member of the valve from becoming stuck), etc.

FIG. 1 illustrates an example process control system 100 that includesan example controller apparatus or device 102 described herein havingone or more pre-defined error-state condition(s) or instructions(s). Asshown in FIG. 1, the example process control system 100 iscommunicatively coupled to a control system 104 (e.g., a control roomsystem) via a communication network 106. In general, communicationchannels, links and paths that enable the controller apparatus 102 tofunction within the process control system 100 are commonly collectivelyreferred to as the communication network 106. In the example of FIG. 1,the communication network 106 includes a wireless communication network.Although not shown, in other examples, the communication network 106 maybe a hardwired communication system.

The example process control system 100 of FIG. 1 includes a field deviceor sensor 108 (e.g., a wireless transmitter or sensor) to monitor orsense a process parameter (e.g., a pressure, a fluid level, etc.) of aprocess fluid (e.g., liquid, gas, etc.) within a fluid containmentapparatus or tank 110. To control fluid flow from the tank 110, theprocess control system 100 employs a field device 112 fluidly coupled tothe tank 110. As shown in FIG. 1, the field device 112 of FIG. 1includes a flow control apparatus or control valve 114 having theexample controller apparatus 102 to control the operation of the flowcontrol apparatus 114 as described in detail below. As shown in FIG. 1,the process control system 100 may include another or second fielddevice 116 to control the flow of fluid into the tank 110. The secondfield device 116 may include a flow control apparatus or control valve118 and another or second example controller apparatus 120 describedherein to control the operation of the flow control apparatus 118.

The example communication network 106 of FIG. 1 communicatively couplesthe wireless field devices 108, 112 and 116 and a control system 122(e.g., a host system, a controller, an alarm system, or other system)via at least one wireless interface 124 (e.g., a gateway). For example,the control system 122 may be in a control room remotely located fromthe field devices 108, 112 and 116. The wireless interface 124 iscommunicatively coupled to the control system 122 via a connection 126such as, for example, an Ethernet connection, a Modbus Ethernetconnection, a serial R485 connection and/or any other suitableconnection(s). The wireless interface 124 may also support or make useof communication standards and protocols such as, for example, a localinterface, a serial modbus, a remote interface, Modbus TCP/IP, HART orany other suitable communication standard(s) and/or protocol(s).Additionally, the wireless interface 124 may serve as a communicationhub.

In some examples, the wireless field device 112 may be enabled toperform wireless communications with other enabled wireless fielddevices such as the wireless field device 108 or 116 and/or one or morewireless interfaces such as the wireless interface 124. Specifically,each of the wireless field devices 108, 112 and 116 may be configured tocommunicate via one or more wireless communication channels, paths orlinks 128 a, 128 b and 128 c. Thus, each of the wireless field devices108, 112 and 116 may communicate with the wireless interface 124 viamultiple or redundant communication paths 128 a-f.

Additionally, the field devices 108, 112 and/or 116 may be at nodes of amesh network (e.g., a full or partial mesh topology) and, thus, maycommunicate simultaneously with other wireless enabled field devicesand/or wireless interfaces (e.g., other gateways, routers or repeaters)within the process control system 100. In some examples, the wirelesscommunication network 106, including the hardware and softwareassociated therewith, provides point-to-point or direct communicationpaths that are selected during installation and fixed during subsequentoperation of the system.

The example flow control apparatus 114 of FIG. 1 includes the valve 130,a pneumatic actuator 132 (e.g., a diaphragm or piston actuator) and aposition sensor 134. The position sensor 134 may be, but not limited to,a non-contact sensor such as, for example, a linear array of Hall-effectsensors that output an analog signal having different values (e.g.,voltages or currents) for different positions of a travel indicatorcoupled to a stem of the valve 130 and/or the actuator 132. Otherexample position sensors may include limit switches, contacts, andpotentiometer-based position sensors. The example valve 130 of FIG. 1provides an orifice (e.g., defined by a valve seat) and a fluid flowpassageway between an inlet 136 and an outlet 138. The example actuator132 of FIG. 1 is operatively coupled to a flow control member 140 via avalve stem 142, which moves the flow control member 140 in a firstdirection (e.g., away from an orifice) to allow a greater fluid flowbetween the inlet 136 and the outlet 138 and a second direction (e.g.,toward an orifice) to restrict or prevent fluid flow between the inlet136 and the outlet 138 based on a pressure differential provided acrossa sensing element of the actuator 132 via a control fluid (e.g., air).The flow control apparatus 114 employs the position sensor 134 to detector sense the position of the flow control member 140 relative to theorifice. The position sensor 134 may be configured to generate a signalrepresentative of the position of the valve 130.

In other examples, the controller apparatus 102 may be employed tocontrol other types of actuators such as, for example, an electric, ahydraulic actuator, etc. For example, when operatively coupled to ahydraulic actuator, the controller apparatus 102 may provide electroniccontrol signals to an electric actuator and/or may provide a signalrepresenting a hydraulic control fluid pressure to be provided to ahydraulic actuator.

In operation, the field device or sensor 108 monitors a fluid level inthe tank 110 and generates a signal representative of the fluid level inthe tank 110. A transmitter of the field device 108 broadcasts orcommunicates the signal to the control system 122 and/or to the fielddevices 112 and 116 via the communication network 106. In addition, thefield devices 112 and 116 may be configured to broadcast or communicatesignals generated by the controller apparatus 102 and 120 correspondingto positions of the respective field devices 112 and 116 to the controlsystem 122 via the communication network 106 and/or may also beconfigured to receive a command signal from the control system 122 viathe communication network 106. For example, the controller apparatus 102may receive a control signal from the control system 122 to move thevalve 130 to a closed position to prevent fluid flow from the tank 110.

When the control system 122 receives a signal from the field device 108corresponding to a fluid level in the tank 110 that is greater than adesired level, the control system 122 sends a control signal to thecontroller apparatus 102 to move the valve 130 to an open position toallow fluid to flow from the tank 110. For example, the controllerapparatus 102 receives a control signal (e.g., a 4-20 milliamps (mA)control signal, a 0-10 volts direct current (VDC) control signal, adigital control signal, etc.) from the control system 122, and thecontroller apparatus 102 converts the control signal(s) into pneumaticor hydraulic pressures that are provided to the actuator 132 viapassageways 144 a and/or 144 b to move the valve 130 to the openposition. Alternatively, in other examples, the controller apparatus 102may be configured to convert and/or send one or more electric signals toan electric actuator to move a valve to an open position. For example,if a process control routine of the control system 122 determines thatthe valve 130 is to permit the passage of a greater volume and/or rateof flow of a process fluid, the magnitude of the control signal suppliedto the controller associated with the valve may be increased from 4 mAto 8 mA, assuming the use of a current type of control signal.

However, in operation, one or more operating parameters of the processcontrol system 100 can deviate from a non-error condition (e.g., anormal operating condition). Deviation from a non-error condition mayaffect the functionality of a flow control assembly and/or may affectthe ability to control the field device 112. As a result, for example,the valve 130 (e.g., the position of the flow control member 140relative to the orifice) may remain in its last current position when anerror-condition occurs (provided that the control fluid to the flowcontrol assembly is in a non-fail condition).

For example, deviation from a non-error condition may occur when acommunication between the control system 122 and the field devices 108,112 and/or 116 is interrupted or stalled. For example, electric power tothe control system 122 may fail or a control signal (e.g., provided by apoint-to-point communication path) may be blocked or degraded and, thus,may not be able to effectively communicate with the field devices 108,112 and/or 116, thereby reducing the accuracy and reliability of theprocess control system 100. In some examples, a temperature surroundingthe controller apparatus 102 may elevate to a temperature greater than asuggested operating temperature. In some instances, a calibration rangeor value of the controller apparatus 102 and/or the position sensor 134may deviate from a pre-set calibrated range or value.

As described in greater detail below, the controller apparatus 102includes pre-defined error-state conditions or instructions that enablethe controller apparatus 102 to control the field device 112 (e.g., thevalve 130) when one or more of the operating parameters deviate from anon-error condition. For example, the controller apparatus 102 mayinclude pre-defined error-state instructions (e.g., commands) thatenable the controller apparatus 102 to move the flow control member 140of the valve 130 to a pre-defined position based on the pre-definederror-state instruction(s) if communication between the control system122 and the controller apparatus 102 is interrupted. In some examples,when an error-state condition is detected, the controller apparatus 102can override a control signal provided by the control system 122 andinstead operate the field device 112 based on the pre-definederror-state instruction(s) until the error condition is resolved.

Additionally or alternatively, an operational action of the field device112 may be dependent upon a position of another field device of theprocess system 100 such as the second field device 116 of FIG. 1. Morespecifically, the example controller apparatus 102 described herein maybe configured to receive a status signal from the controller apparatus120 of the second field device 116, the operation of which precedes theoperation of the field device 112. In that case, the controllerapparatus 102 operates the field device 112 only if the second fielddevice 116 is in a proper position. In some instances, the controllerapparatus 102 may override a command signal (e.g., a coordinated signal)received from the control system 122 if the second field device 116 isnot in a proper position.

For example, referring to the example of FIG. 1, the field device 108may broadcast a signal to the control system 122 and/or the controllerapparatus 102 and 120 that a fluid level in the tank 110 is at a desiredlevel. A process control routine of the control system 122 may determinethat the valves 130 and 118 are to move to a closed position in acoordinating manner and the control system 122 configures a coordinatedcontrol signal based on that determination and communicates that signalto the controller apparatus 102 and 120 to move each of the valves 130and 118 to their closed positions. However, a pre-defined error-stateinstruction may cause the controller apparatus 102 to delay moving thevalve 130 to the closed position if the controller apparatus 120broadcasts a signal representative of the valve 118 being in a positionother than the closed position. In this manner, if the controllerapparatus 102 receives a signal from controller apparatus 120 indicatingthat the position of the valve 118 is not in the closed position, thecontroller apparatus 102 may not move the valve 130 to closed positionbecause doing so may cause the fluid level in the tank 110 to rise,regardless of the control signal communicated by the control system 122.

In yet other examples, when an error condition occurs, the controllerapparatus 102 may be configured to cause the valve 130 to move to aspecific stroke position or intermediate position. For example, thespecific stroke position may be between zero percent stroke andone-hundred percent stroke. For example, the controller apparatus 102may cause the valve 130 to move a 10% stroke position (i.e., 10% open).In yet other examples, when an error-condition is detected, thecontroller apparatus 102 may be configured to move the valve 130 to afirst position for a first duration or amount of time and a secondposition for a second duration or amount of time. For example, thecontroller apparatus 102 may cause the valve 130 to move to an 85% openposition for a first hour after detection or occurrence of the errorcondition and may subsequently cause the valve 130 to move to a 15% openposition after the first hour from detection or occurrence of the errorcondition. In yet other examples, when an error condition is detected,an error-state instruction may command the controller apparatus 102 todelay operating the field device 112 after a pre-set duration from thedetection of the error condition lapses (e.g., one-hour from errorcondition detection).

Although the example of FIG. 1 illustrates the field device 112 as avalve 130, the example apparatus and methods described herein topre-define fail state setting(s) may be used with other devicesincluding, but not limited to, a final control element, a flow controldevice, a pump, a vent, a louver or any other device(s). Additionally oralternatively, while an example actuator 132 of FIG. 1 is depicted as adouble-acting diaphragm or piston actuator, any other type(s) ofactuator(s) such as, for example, a rotating actuator, a single-actingspring return diaphragm or piston actuator, an electric actuator, ahydraulic actuator, etc., may alternatively be used.

FIG. 2 is block diaphragm of the example controller apparatus 102 ofFIG. 1. In the illustrated example, the controller apparatus 102 is awireless electro-pneumatic valve position controller 102 mounted to or,alternatively, disposed proximate to a field device such as, forexample, the field device 112 of FIG. 1. The example valve positioncontroller 102 described herein may be operatively coupled to the fielddevice 112 to provide wireless valve position monitoring and pneumaticcontrol of the field device 112. However, in other examples, thecontroller apparatus 102 may be a position transmitter, a transceiver, atransducer and/or any other controller for controlling a field devicesuch as, for example, a final control element, an electric actuator, ahydraulic actuator, a pump, a vent, a louver etc.

Referring to FIGS. 1 and 2, the controller apparatus 102 includes ahousing 202 to hold a processor 204, a communication interface 206, afield device control module and/or fluid device control module 208, aposition interface 210, an error condition detector 212, a pre-definederror-state condition module 214, a memory 216, an input interface 218and a power supply 220. The power supply 220 may receive alternatingcurrent, direct current or may be loop powered. Additionally oralternatively, the power supply 220 may include a self-contained powermodule (e.g., a battery pack). Thus, the controller apparatus 102 may bea self-powered controller.

To communicate with (e.g., send/receive information to) a control systemor another field device such as the control system 122 and/or the fielddevices 108 and 116 of FIG. 1, the example controller apparatus 102includes the communication interface 206. For example, the examplecontroller apparatus 102 described herein may convey information (e.g.,position information received from the position sensor 134 of the fielddevice 112) to a control system (e.g., the control system 122 of FIG. 1)for processing. The control system 122 may then process the positioninformation (e.g., to determine whether the valve should beopened/closed) and return appropriate commands to the processor 204 viathe communication interface 206. The communication interface 206provides the instructions to the processor 204 via a path or link 222.Thus, the example controller apparatus 102 is capable of collecting andrelaying information and receiving information and/or commands from thecontrol system 122 or other field devices 108 and 116 to directlycontrol the field device 112 via the communication interface 206.

The processor 204 processes a control signal received from thecommunication interface 206 and communicates the signal to the fielddevice control module 208 via a path or link 224, which controlspneumatic pressures supplied to the chambers of the actuator 132 by acontrol fluid 226 (e.g., pneumatic control fluid). For example, theprocessor 204 and/or the field device control module 208 may convert(e.g., via an I/P converter) an electronic command or signal (e.g., avoltage, a current, etc.) received by the communication interface 206 togenerate a pneumatic signal (e.g., a proportional pressure signal) thatmay be used to control the field device 112 in accordance with thecommands received by the communication interface 206 (e.g., instructionssent by the control system 122). Based on pressure control valuesprovided by the processor 204, the field device control module 208determines whether to increase or decrease the pneumatic pressures to beprovided to the field device 112 via the fluid passageways 144 a and 144b. For example, the field device control module 208 may include a valveor flow control apparatus to control the amount of control fluid 226 toflow to the passageways 144 a and 144 b. In some examples, the fielddevice control module 208 may include a pneumatic amplifier to amplifythe supply fluid signal. In other examples, as noted above, thecontroller apparatus 102 may be configured to control an electricactuator or other final control element. In such an example, the fielddevice control module 208 may provide an electric signal or otherinstruction(s) or command(s) to a pump device to operate a pump, anelectric actuator to move a valve coupled to the electric actuator,and/or any other final control element and/or flow control device(s)

As the field device 112 (e.g., the actuator 132) operates, the positioninterface 210 monitors a position of the field device 112. For example,the position interface 210 receives a feedback signal 228 from theposition sensor 134 corresponding to the position of the field device112 (e.g., the flow control member 140 of FIG. 1) based on the pressuredifferential provided to the actuator 132 of the field device 112 viathe field device control module 208. The position interface 210communicates the position information to the processor 204 via a link orpath 230. In turn, the processor 204 processes the position informationand the communication interface 206 broadcasts or communicates theposition information to a communication network (e.g., the communicationnetwork 106 of FIG. 1).

Thus, when the process control system 100 of FIG. 1 is in a non-failstate or non-error condition, the processor 204 processes instructionsreceived by the communication interface 206 to control the field device112 and/or communicate status information of the field device 112 viathe communication interface 206.

To detect if an error condition has occurred, the example controllerapparatus 102 employs the error condition detector 212. An errorcondition is detected when a pre-defined process parameter of the fielddevice 112, the controller apparatus 102 and/or other parameters orconditions of the process control system 100 of FIG. 1 deviate from anon-error condition. For example, when the error condition detector 212detects an error condition has occurred, the error condition detector212 communicates the detection of the error condition to the processor204 via a path or link 232. In such instances, the processor 204 may notreceive or process instructions provided by the communication interface206. Instead of receiving or processing instructions received from thecommunication interface 206, the processor 204 processes and/or receivesinstructions provided by an alternative source to control or operate thefield device 112. In the illustrated example, the alternative source isprovided by the pre-defined error-state condition module 214. Forexample, when the error condition detector 212 detects an errorcondition, the pre-defined error-state condition module 214 providescontrol instructions to the processor 204 via a link 234. Additionallyor alternatively, in some examples, the processor 204 may receive orprocess partial instructions from the communication interface 206 andpartial instructions from the pre-defined error-state condition module214 to control or operate the field device 112. In some examples, theprocessor 204 may receive a first pre-defined error-state instruction orcommand based on a first error condition detected and a secondpre-defined error-state instruction or command based on a second errorcondition detected.

A pre-defined error-state instruction(s) or command(s) corresponding toan error condition may be programmable or configurable by a user. Forexample, a user may define a process parameter value or limit and theerror condition detector detects whether the error condition hasoccurred when the process parameter value or limit is exceeded ordeviates from the assigned, selected and/or configured non-errorcondition.

As shown in FIG. 2, the example error condition detector 212 includes acommunication detector 236, a temperature detector 238, a positiondetector 240, a calibration detector 242 and a dependent field devicedetector 244.

The communication detector 236 detects a communication error with thecommunication network 106, the control system 122 and/or the fielddevices 108 and/or 116. For example, if the communication detector 236detects a communication interruption in the link or path 222 between thecommunication interface 206 and the processor 204, then thecommunication detector 236 sends a signal to the processor 204 toreceive a pre-defined error-state instruction from the pre-definederror-state condition module 214. In turn, the pre-defined error-statecondition module 214 provides a pre-defined error-state instruction orcommand that corresponds to the detection of a communication error. Forexample, the pre-defined condition or instruction may command theprocessor 204 to operate the field device 112 to, for example, an openposition, a closed position, a throttling position or any other positionbetween the open and closed positions if a communication error isdetected by the error condition detector 212. In some examples, anotherpre-defined error-state instruction may instruct the processor 204 todelay operating the fluid device 112 for a first period of time (e.g.,begin operation one-hour after detection of an error condition). In someexamples, the pre-defined error-state instruction may cause theprocessor 204 to control the field device 112 to a position (e.g., anopen position) to allow draining the tank 110 for a specified amount oftime without monitoring the actual fluid level in the tank 110.

The temperature detector 238 detects a temperature surrounding thecontroller apparatus 102. For example, the temperature detector 238 mayreceive a measured temperature value from a temperature sensor of thecontroller apparatus 102 and/or the process control system 100. Thetemperature detector 238 compares via, for example, a comparator themeasured temperature value provided by the temperature sensor and atemperature threshold value that, for example, may be stored in thememory 216. As noted above, the temperature threshold value may bepre-defined or user selectable via the input interface 218. If themeasured temperature value is greater than the temperature thresholdvalue, the temperature detector 238 sends a signal to the processor 204.In turn, the pre-defined error-state condition module 214 provides theprocessor 204 with a pre-defined error-state instruction or commandassociated with detection of a temperature greater than the thresholdvalue. For example, the pre-defined error instruction may command theprocessor 204 to power down. In some examples, the pre-definederror-state instruction may cause the processor 204 to move the fielddevice to an open position or a closed position prior to powering down.

The position detector 240 determines if a position command signalprovided to the processor 204 by the communication interface 206 and/orthe pre-defined error-state condition module 214 correlates with ameasured position value (e.g., the position signal 228) provided to theposition interface 210 by the position sensor 134. For example, theposition detector 240 may compare via, for example, a comparator theposition command signal and the measured position value to determine ifthe field device 112 is in the proper position. If the position detector240 determines that the measured position value does not correlate withthe position command signal, the pre-defined error-state conditionmodule 214 provides the processor 204 with a pre-defined error-stateinstruction or command associated with detection of an improper positionof the field device 112. For example, the pre-defined error-statecondition module 214 may send or broadcast a warning or maintenancesignal to the communication network 106 via the communication interface206. Additionally or alternatively, the example pre-defined error-stateinstruction may cause the processor 204 to initiate a maintenanceroutine to periodically or rapidly cycle the field device 112 todetermine if the improper position may be due to a stuck valve.

The calibration detector 242 may be used to determine if a calibrationbetween the controller apparatus 102 and the position sensor 134deviates from a pre-set calibration range or value. If the calibrationdetector 242 detects a deviation from the pre-set calibration range orvalue, the pre-defined error-state condition module 214 provides theprocessor 204 with a pre-defined error-state instruction or commandassociated with detection of a deviation from the pre-set calibratedsetting or range. For example, the pre-defined error-state conditionmodule 214 may cause the processor 204 to initiate an automaticre-calibration routine and/or initiate a maintenance alert.

The dependent field device detector 244 detects if an operation of thefield device 112 is dependent on an operation or action of another fielddevice (e.g., the second field device 116 of FIG. 1) of the processcontrol system 100. For example, in some instances, an operation of thesecond field device 116 may need to precede the operation and/orcoordinate with the operation of the field device 112. If the dependentfield device detector 244 determines that the operation of the fielddevice 112 is dependent on the operation of the second field device 116occurring first (or simultaneously), then the error condition detector212 sends a signal to the processor 204 and/or the pre-definederror-state condition module 214. In turn, the pre-defined error-statecondition module 214 provides the processor 204 with a pre-definederror-state instruction or command associated with detection of anoperation of the field device 112 being dependent on the operation ofthe second field device 116. For example, during a maintenance process,the control system 122 may broadcast or communicate a signal tocontroller apparatus 102 and 120 to move the respective field devices112 and 116 to a closed position (e.g., simultaneously). However, if thecontroller apparatus 120 of the second field device 116 broadcasts asignal indicating that the field device 116 is not in a closed position,the example dependent field device detector 244 sends a signal to theprocessor 204 and the dependent field device detector 244 determinesthat an error condition has occurred. In turn, a pre-defined error-stateinstruction may direct the processor 204 to delay, ignore, or overridethe command signal of the control system 122 until the dependent fielddevice detector 244 determines that the second field device 116 is in aproper position.

As noted above, in the illustrated example, an error condition and/or apre-defined error-state instruction or command may be user configurableor programmable. Some example pre-defined error-state instructions orcommands may cause a field device such as, for example, the field device112 to move to a fully open position, a fully closed position, athrottling position, and/or any other position between the fully openposition and the fully closed position such as, for example, a 10% openposition, a 80% open position, etc.

In some examples, the pre-defined error-state instruction may instructthe processor 204 to change or move the output or position of the fielddevice 112 (e.g., from a closed position to an open position) for aperiod of time (e.g., 15 minutes, 5 hours, etc.), and then return to theprevious output state or position (e.g., the closed position).

In yet other examples, the pre-defined error-state instructions mayinstruct the processor 204 to maintain a last current position of thefield device 112 upon detection of an error condition by the errorcondition detector 212 (e.g., a fail-last position). In such instances,such a fail-last position may be provided without any pneumatic output.For example, the processor 204 may instruct the field device controlmodule 208 to maintain the control fluid in the chambers of the actuator132 such that the field device control module 208 does not exhaust thecontrol fluid in the actuator 132 via an exhaust 246.

In some examples, pre-defined error-state instructions may command theprocessor 204 to move the field device 112 to any pre-selected position(e.g., a fail-set position) with or without the pneumatic output or useof the field device control module 208 and/or the control fluid 226. Forexample, for positioning the field device 112 without pneumatic output,the processor 204 may instruct the field device control module 208 toexhaust pressure from at least one of the chambers of the actuator 132via the exhaust 246 to move the field device 112 to the fail-setposition. For example, if a field device includes a single acting,spring loaded actuator, exhausting the control fluid from a controlchamber of the actuator will cause the spring to move a flow controlmember of a valve to a fully open position or a fully closed positionwithout the use of the control fluid 226.

Additionally or alternatively, the pre-defined error-state instructionmay instruct the field device 112 to move to a first position for afirst duration after the error condition detector 212 detects an errorcondition and may instruct the field device 112 to move to a secondposition for a second duration subsequent to the expiration of the firstduration if the error condition detector 212 detects that the errorcondition is not resolved upon the expiration of the first duration.

An error condition(s) and/or a pre-defined error-state instruction maybe programmable via the input interface 218. The input interface 218 mayinclude a display (e.g., an LCD display, a touch-screen display, etc.)having an input module (e.g., a keypad, push buttons, etc.) to receiveinput information from, for example, a user or operator. In addition,the input interface 218 may include an override option (e.g., a button)to enable an operator or user to override commands or instructionsprovided by the communication interface 206 and/or the pre-definederror-state condition module 214. In such instances, the processor 204may receive instructions or commands via the input interface 218.

The controller apparatus 102 of the illustrated example also includesthe memory 216 to store pre-defined error-state commands orinstructions. For example, if an error condition is detected by theerror condition detector 212, the pre-defined error-state conditionmodule 214 may retrieve from the memory 216 one or more pre-definederror-state instruction(s) that correlate to the detected errorcondition.

Additionally or alternatively, the example controller apparatus 102 mayinclude a maintenance and/or diagnostic routine. Amaintenance/diagnostic initiator 250 initiates a routine that mayinclude initiating, for example, a warning or an alarm, a reminder. Insome examples, the maintenance/diagnostic initiator 250 initiates acommunication (e.g., instructions or commands) to the processor 204 whenthe maintenance/diagnostic initiator 250 detects that the field device112 has not moved as commanded, has stayed in a certain position for arelatively long period of time, a maintenance schedule was missed ordelayed, etc. In some instances, to prevent the field device 112 frombecoming stuck due to inactivity, the example maintenance/diagnosticinitiator 250 may periodically initiate an operation of the field device112 (e.g., instructions to cycle the field device 112). Amaintenance/diagnostic routine may be programmed to automaticallyinitiate at any desired date, time, occurrence (e.g., reoccurring) etc.For example, an automated maintenance schedule may be stored in thecontroller apparatus 102 via the user input interface 218.

While an example manner of implementing the controller apparatus 102 ofFIGS. 1 and 2 has been illustrated in FIG. 2, one or more of theelements, processes and/or devices illustrated in FIG. 2 may becombined, divided, re-arranged, omitted, eliminated and/or implementedin any other way. Further, the example pre-defined error-state conditionmodule 214, the example error condition detector 212 and/or, moregenerally, the example the controller apparatus 102 of FIGS. 1 and 2 maybe implemented by hardware, software, firmware and/or any combination ofhardware, software and/or firmware. Thus, for example, any of theexample pre-defined error-state condition module 214, the errorcondition detector 212, and/or, more generally, the example controllerapparatus 120 of FIGS. 1 and 2 could be implemented by one or morecircuit(s), programmable processor(s), application specific integratedcircuit(s) (ASIC(s)), programmable logic device(s) (PLD(s)) and/or fieldprogrammable logic device(s) (FPLD(s)), etc. The example controllerapparatus 102 may include one or more elements, processes and/or devicesin addition to, or instead of, those illustrated in FIG. 2, and/or mayinclude more than one of any or all of the illustrated elements,processes and devices.

FIGS. 3-5 are flowcharts representative of example methods that may beused to control, operate and/or otherwise implement the examplecontroller apparatus 102 of FIGS. 1 and 2. While example methods 300,400 and 500 have been illustrated in FIGS. 3-5, one or more of theoperations illustrated in FIGS. 3-5 may be combined, divided,re-arranged, omitted, eliminated and/or implemented in any other way.Further still, the example methods of FIGS. 3-5 may include one or moreoperations in addition to, or instead of, those illustrated in FIGS.3-5, and/or may include more than one of any or all of the illustratedoperations. Further, although the example method is described withreference to the flow chart illustrated in FIGS. 3-5, many other methodsof detecting an error condition of a process control system mayalternatively be used.

FIG. 3 is a flowchart representative of an example method that may beused to implement the example controller apparatus 102 of FIGS. 1 and 2.

Referring to FIG. 3, the controller apparatus 102 is provided with apre-defined error-state instruction that corresponds to a detected errorcondition (block 302). For example, the pre-defined error-stateinstruction and/or the corresponding error condition may beprogrammable. For example, a pre-defined error-state instruction may bepre-installed (e.g., at the factory) in the controller apparatus 102and/or may be provided to the controller apparatus 102 afterinstallation of the controller apparatus 102 to the field device 112(e.g., in the field). In some examples, the pre-defined error-stateinstruction and/or corresponding error condition may be user programmedinstructions or commands that may be input to the controller apparatus102 via the input interface 218 as described above.

During operation, the controller apparatus 102 operates the field devicebased on a command signal received from a control system (block 304).For example, if the controller apparatus 102 does not detect that anerror condition has occurred, the processor 204 operates the fielddevice 112 based on a control signal or instruction provided by thecontrol system 122 via the communication interface 206.

Also, during operation, the controller apparatus 102 and/or the errorcondition detector 212 detects whether an error condition has occurred(block 306). For example, the error condition detector 212 monitors oneor more process control system parameters or settings associated with anerror condition stored in the controller apparatus 102. For example, theerror condition detector 212 monitors communication via thecommunication detector 236, a temperature via the temperature detector238, a field device position via the position detector 240, acalibration via the calibration detector 242 and/or an interlock processor cascade process via the dependent field device detector 244.

If an error condition is detected by, for example, the error conditiondetector 212, the controller apparatus 102 obtains or retrieves apre-defined error-state instruction that corresponds to the errorcondition detected (block 308). For example, the processor 204 mayretrieve or obtain the pre-defined error-state instruction from thepre-defined error-state condition module 214.

The controller apparatus 102 operates or controls the field device 112based on the pre-defined error-state instruction (block 310). Forexample, the processor 204 may receive a pre-determined error-stateinstruction to move the field device 112 to a closed position upondetection of a communication error condition provided by thecommunication detector 236. The processor 204 may command the fielddevice control module 208 to provide control fluid 226 to an upperchamber of the actuator 132 to move the flow control member 140 towardthe orifice to restrict or prevent fluid flow through the passageway ofthe valve 130. In other examples, the pre-defined error-stateinstructions may command or operate a final control element such as, forexample, an electrically actuated valve, a pump, a vent and/or any othersuitable field device(s) or final control element(s). In some examples,the pre-defined error-state instructions may be high pressure signalsused with hydraulic actuated valves or final control elements.

FIG. 4 is a flowchart representative of an example process to controlthe example controller apparatus 102 of FIGS. 1 and 2.

To detect an error condition, the example processor 204 and/or errorcondition detector 212 determine if an error condition and/or anerror-state instruction is stored or otherwise configured in thecontroller apparatus 102 (block 402). For example, the processor 204and/or the error condition detector 212 determine whether a pre-definederror-state condition has been stored in the memory 216 of thecontroller apparatus 102. If the pre-defined error-state condition hasnot been provided or defined, then the process 400 ends.

If the processor 204 and/or the error condition detector 212 determinethat a pre-defined error-state condition is provided at block 402, thenthe processor 204 and/or the error control detector 212 monitor one ormore system condition(s) and/or parameter(s) of the process controlsystem 100 of FIG. 1 that correspond to the pre-defined error-statecondition configured in the controller apparatus 102 (block 404). Asmentioned above, an example system condition and/or parameter that canbe configured includes, but is not limited to, a network communication,a temperature value, a calibration setting, a position value,coordinated operation of multiple field devices, and/or any otherprocess control system condition(s) and/or parameter(s) that can bemonitored.

The processor 204 and/or the error condition detector 212 then runs orexecutes an error condition detection process to detect an errorcondition (block 406). For example, the processor 204 and/or the errorcondition detector 212 may detect an error condition based on themonitored system conditions and/or parameters information received atblock 404. An example error condition detection process 500 that may beused to implement block 406 is described in connection with FIG. 5.

If the processor 204 and/or the error condition detector determine thatan error condition has not occurred at block 406, the process 400returns to block 404 (block 408). For example, if an error condition isnot detected at block 406, then the processor 204 continues to controlor operate the field device 112 based on instructions received via thecommunication interface 206. If the error condition detector 212 detectsan error condition, then the error condition detector 212 provides asignal to the processor 204 indicating that an error condition hasoccurred (block 408).

The processor 204 and/or the error condition detector 212 access,obtain, or receive the pre-defined error-state instructionscorresponding to the detected error condition. (block 410). For example,the pre-defined error-state condition module 214 may retrieve from thememory 216 the pre-defined error-state instructions corresponding to thespecific error condition detected at block 406, and/or may send orprovide the pre-defined error-state instruction(s) to the processor 204.The processor 204 then operates the field device 112 according to thepre-defined error-state instruction(s) associated with the errorcondition detected at block 404 (block 412).

The processor 204 then determines if the detected error condition isresolved (block 414). If the detected error condition is not resolved atblock 414, then the processor 204 continues to operate the field device112 according to the pre-defined error-state instructions obtained atblock 412. If the detected error condition is resolved, then thecontroller apparatus 102 returns to non-error condition settings (block416). When the controller apparatus 102 returns to a non-errorcondition, the processor 204 controls the field device 112 viainstructions received by the communication interface 204 (e.g.,instructions provided by the control system 122).

FIG. 5 is a flowchart representative of an example error conditiondetection process that may implement the block 406 of FIG. 4.

To determine an error condition, the error condition detector 212analyzes or processes the monitored system conditions and/or parametersobtained at block 404 of FIG. 4 (block 502). For example, the errorcondition detector 212 may analyze, measure and/or process the monitoredsystem conditions and/or parameters for each of the pre-defined errorcondition configured in the controller apparatus 102.

The error condition detector 212 then determines if the monitored systemcondition(s) and/or parameter(s) deviate from a non-error condition(block 504). If the monitored system condition(s) or parameter(s) do notdeviate from the non-error condition at block 504, then the errorcondition detector 212 determines that an error condition is notdetected (block 506). The process 500 then returns to block 406 of FIG.4.

If the monitored system condition(s) or parameter(s) deviate from thenon-error condition at block 504, then the error condition detector 212determines that an error condition is detected (block 508). The process500 then returns to block 406 of FIG. 4.

FIG. 6 is a block diagram of an example processor system that may beused to implement the example methods and apparatus described herein.The processor system 610 of FIG. 6 includes a processor 612 that iscoupled to an interconnection bus 614. The processor 612 may be anysuitable processor, processing unit, or microprocessor (e.g., one ormore Intel® microprocessors from the Pentium® family, the Itanium®family or the XScale® family, Texas Instruments® embedded processors,and/or other processors from other families). The system 610 may be amulti-processor system and, thus, may include one or more additionalprocessors that are identical or similar to the processor 612 and thatare communicatively coupled to the interconnection bus 614.

The processor 612 of FIG. 6 is coupled to a chipset 618, which includesa memory controller 620 and an input/output (I/O) controller 622. Achipset provides I/O and memory management functions as well as aplurality of general purpose and/or special purpose registers, timers,etc. that are accessible or used by one or more processors coupled tothe chipset 618. The memory controller 620 performs functions thatenable the processor 612 to access a system memory 624 and a massstorage memory 625, and/or a digital versatile disk (DVD) 640.

In general, the system memory 624 may include any desired type ofvolatile and/or non-volatile memory (NVM) such as, for example, staticrandom access memory (SRAM), dynamic random access memory (DRAM), flashmemory (FRAM), read-only memory (ROM), etc. The mass storage memory 625may include any desired type of mass storage device including hard diskdrives, optical drives, tape storage devices, etc. The machine readableinstructions of FIGS. 4 and 5 may be stored in the system memory 624,the mass storage memory 625, and/or the DVD 640.

The I/O controller 622 performs functions that enable the processor 612to communicate with peripheral input/output (I/O) devices 626 and 628and a network interface 630 via an I/O bus 632. The I/O devices 626 and628 may be any desired type of I/O device such as, for example, akeyboard, pushbuttons, a video or other local user interface display ormonitor, a mouse, etc. The network interface 630 may be, for example, anEthernet device, an asynchronous transfer mode (ATM) device, an 802.11device, a DSL modem, a cable modem, a cellular modem, HART communicatingprocess control system, any fieldbus communication systems similar toFoundation Fieldbus and Profibus, etc. that enables the processor system610 to communicate with another processor system. The example networkinterface 630 of FIG. 6 is also communicatively coupled to a network634, such as an intranet, a Local Area Network, a Wide Area Network, theInternet, etc.

While the memory controller 620 and the I/O controller 622 are depictedin FIG. 6 as separate functional blocks within the chipset 618, thefunctions performed by these blocks may be integrated within a singlesemiconductor circuit or may be implemented using two or more separateintegrated circuits.

FIG. 7 is a flowchart representative of an example method of installingthe controller apparatus 102 described in FIG. 1. To install thecontroller apparatus 102, the controller apparatus is mounted to a fielddevice (e.g., the actuator 132 of the field device 112) and/or may becoupled proximate to the field device via a mounting or bracket (block702). The controller apparatus 102 is then operatively coupled to thefield device 112 (block 704). For example, the passageways 144 a and 144b are coupled to the field device control module 208 and the actuator132. Additionally, the controller apparatus 102 is operatively coupledand/or configured to communication the control system 122 and/or otherfield devices (e.g., the field devices 108 and 118) via thecommunication network 106 (block 706).

In some examples, the controller apparatus may prompt for selection ofthe pre-defined error conditions (block 708). For example, thepre-defined error conditions may be selected from a drop down menupresented to a user or technician via the input interface and/or thepre-defined error conditions may be programmed in the controllerapparatus 102 via, for example, a computer.

The pre-defined error conditions are then provided or configured (block710). In some examples, the pre-defined error conditions may be factoryinstalled and/or may be configured in the field. Once the errorconditions are provided or configured, the pre-defined error-stateinstructions corresponding to each of the selected or definedpre-determined error conditions are provided or configured (block 712).As noted above, such pre-defined error-state instructions may beprogrammable, user defined, and/or customized per a user's requirements.

Although certain example methods and apparatus have been describedherein, the scope of coverage of this patent is not limited thereto. Onthe contrary, this patent covers all methods, apparatus and articles ofmanufacture fairly falling within the scope of the appended claimseither literally or under the doctrine of equivalents.

What is claimed is:
 1. A non-transitory computer-readable mediumcomprising instructions that, when executed, cause a machine to:analyze, via a controller coupled to a field control device, acommunication from a control system remotely located from thecontroller, the control system to operate the field control deviceduring a non-error condition; detect an error condition while the fieldcontrol device is communicatively coupled to and receives thecommunication from the control system; and override the communicationbetween the control system and the controller to operate the fieldcontrol device based on a pre-defined error-state instruction stored inthe controller when the error condition is detected to cause the fieldcontrol device to move to a first position for a first amount of timeand subsequently move the field control device to a second position fora second amount of time, the first position being different than thesecond position.
 2. The non-transitory computer-readable medium asdefined in claim 1 comprising instructions that, when executed, causethe machine to detect the error condition by monitoring a processparameter of the field control device via the controller.
 3. Thenon-transitory computer-readable medium as defined in claim 1 comprisinginstructions that, when executed, cause the machine to move the fieldcontrol device to the first position or the second position by movingthe field control device to a fully open position or a fully closedposition.
 4. The non-transitory computer-readable medium as defined inclaim 1 comprising instructions that, when executed, cause the machineto move the field control device to the first position by moving thefield control device to a first intermediate position, and move thefield control device to the second position by moving the field controldevice to a second intermediate position, wherein the first intermediateposition or the second intermediate position is between a fully openposition and a fully closed position.
 5. A non-transitorycomputer-readable medium comprising instructions that, when executed,cause a machine to: operate a field control device via a control signalthat is broadcasted over a network by a process control system; monitoran operating parameter of the process control system; detect an errorcondition based on the operating parameter; and override the controlsignal to control the field control device via a local controlleroperatively coupled to the field control device based on at least onepre-determined error-state instruction stored in the local controllerwhen the error condition is detected and the control signal is receivedby the field control device.
 6. The non-transitory computer-readablemedium as defined in claim 5 comprising instructions that, whenexecuted, cause the machine to monitor the operating parameter bydetermining if a temperature surrounding the controller is greater thana threshold value.
 7. The non-transitory computer-readable medium asdefined in claim 5 comprising instructions that, when executed, causethe machine to monitor the operating parameter by: providing a commandposition value to the controller to move the field control device to adesired operating position; receiving a measured position valuerepresentative of an actual position of the field control device; andcomparing the measured position value and the command position value. 8.The non-transitory computer-readable medium as defined in claim 7comprising instructions that, when executed, cause the machine tooperate the field control device based on the pre-determined error-stateinstruction when a difference between the measured position value andthe command position value is greater than a threshold value.
 9. Thenon-transitory computer-readable medium as defined in claim 5 comprisinginstructions that, when executed, cause the machine to monitor theoperating parameter by: receiving a measured position valuerepresentative of an actual position of the field control device from aposition sensor of the field control device; and comparing the measuredposition value received and a pre-set calibration range.
 10. Thenon-transitory computer-readable medium as defined in claim 9 comprisinginstructions that, when executed, cause the machine to operate the fieldcontrol device by calibrating the field control device if the measuredposition value received is outside of the pre-set calibration range. 11.The non-transitory computer-readable medium as defined in claim 5comprising instructions that, when executed, cause the machine to obtaininformation relating to an operation of another field control devicethat precedes an operation of the field control device.
 12. Thenon-transitory computer-readable medium as defined in claim 11comprising instructions that, when executed, cause the machine tooverride the control signal to control the field control device based onthe pre-determined error-state instruction by delaying the controlsignal provided by the control system when the other field controldevice is not in a proper position.
 13. The non-transitorycomputer-readable medium as defined in claim 5 comprising instructionsthat, when executed, cause the machine to select or define thepre-determined error-state instruction via a user interface.
 14. Thenon-transitory computer-readable medium as defined in claim 5 comprisinginstructions that, when executed, cause the machine to monitor theoperating parameter of the process system by monitoring at least one ofa communication connection, a temperature surrounding the localcontroller, a calibration parameter, or a position parameter.
 15. Thenon-transitory computer-readable medium as defined in claim 5 comprisinginstructions that, when executed, cause the machine to control the fieldcontrol device by causing a fluid valve to move to a closed position viathe local controller when the error condition is detected when the fluidcontrol device is implemented as the fluid valve.
 16. The non-transitorycomputer-readable medium as defined in claim 5 comprising instructionsthat, when executed, cause the machine to enable the process controlsystem to operate the field control device in a non-error condition whenthe detected error condition is resolved.
 17. The non-transitorycomputer-readable medium as defined in claim 5 comprising instructionsthat, when executed, cause the machine to operate the field controldevice based on the pre-determined error state instruction stored in thelocal controller by processing partial instructions provided by theprocess control system.
 18. The non-transitory computer-readable mediumas defined in claim 5 comprising instructions that, when executed, causethe machine to communicatively couple the local controller to theprocess control system via wireless communication.
 19. Thenon-transitory computer-readable medium as defined in claim 5 comprisinginstructions that, when executed, cause the machine to broadcast analert, via the local controller, when the field control device isimproperly positioned or requires maintenance.
 20. The non-transitorycomputer-readable medium as defined in claim 5 comprising instructionsthat, when executed, cause the machine to override the control signal tocontrol the field control device based on the at least onepre-determined error-state instruction by moving the field controldevice to an intermediate position between a fully open position and afully closed position.
 21. The non-transitory computer-readable mediumas defined in claim 5 comprising instructions that, when executed, causethe machine to operate, via the local controller, the field controldevice via the control signal provided from the control system remotelylocated from the local controller during a non-error condition.
 22. Thenon-transitory computer-readable medium as defined in claim 5 comprisinginstructions that, when executed, cause the machine to detect the errorcondition while the field control device is communicatively coupled toand receives the control signal from the process control system.
 23. Anon-transitory computer-readable medium comprising instructions that,when executed, cause a machine to: analyze a command from a controlsystem remotely located from a local controller coupled to a fieldcontrol device; control a position of the field device based on thecommand from the control system during a non-error condition; detect anerror-condition; and override the command from the control system andinstruct the field device based on a pre-defined error-state settingstored in the local controller when the error condition is detectedregardless of the controller receiving the command from the controlsystem.
 24. The non-transitory computer-readable medium as defined inclaim 23 comprising instructions that, when executed, cause the machineto detect the error-condition by determining a temperature surroundingthe controller greater than a threshold value.
 25. The non-transitorycomputer-readable medium as defined in claim 23 comprising instructionsthat, when executed, cause the machine to detect the error-condition bydetermining a position value of the field control device provided by aposition sensor of the field control device and determining if theposition value corresponds to a command position value provided by thecontrol system or the local controller.
 26. The non-transitorycomputer-readable medium as defined in claim 23 comprising instructionsthat, when executed, cause the machine to present a prompt requestingthe pre-defined error-state setting and receive the pre-definederror-state setting via an input device.
 27. The non-transitorycomputer-readable medium as defined in claim 23 comprising instructionsthat, when executed, cause the machine to command the field device viathe command provided by the control system when the detected errorcondition is resolved.